Two coupled pendula
Lecture-room Laboratory


The simulation can be started and paused by pressing the Play/Pause button. The Reset button brings both pendula in their initial positions.

In the upper left corner there are 6 text boxes that can be used to change the parameters from their default values. You can change the

  • mass of the two springs between 0 and 1000 kg,
  • length of both springs between 0 and 2 meter,
  • $ k$ the spring constant between 0 and 1000 N/m,
  • $ c$ the distance between the suspension point of the pendulum and the suspension point of the spring between 0 and the length of the pendula,
  • $ \alpha_0$ (and $ \beta_0$) the initial angles of the left (and right) pendulum between -90 and 90 degrees.

Press enter every time you insert a new value into a text box.

In the lower left corner the angles $ \alpha(t)$ and $ \beta(t)$ are plot. The color of the lines correspond to that of the pendula, blue for the left pendulum and red for the right one.

This applet can be downloaded and run off line on every computer with a Java compatible browser. The source code is also available here.

NOTE: The smoothness of the simulation can vary on different systems (different operating systems, Internet browsers, or computer configurations). The applet runs best on a windows machine running the latest version of Internet explorer.
Go back home Authors: Bastiaan Huisman & Annalisa Fasolino
Date: april 20 2001
Selected by a service of National Science Teachers Association. Copyright 1999 - 2002.